case history of a “brownfields” site in wichita, …...paper from: brownfield sites, ca brebbia,...

Case history of a “Brownfields” site in Wichita,Kansas USA: innovative approaches togroundwater remediation

R.L. Olsenl, J. Brown2, &P. Anderson31CDM, Denver, Colorado USA‘Department of Environmental Health, Wichita, Kansas USA3 CDM, Kansas City, Missouri USA

Abstract

At the Gilbert-Mosley Site in Wichita, Kansas USA, the groundwater has beencontaminated by chlorinated solvents from past industrial activities. Over 3billion gallons of groundwater have concentrations of tetrachloroethene (PCE)and trichloroethene (TCE) above drinking water standards (maximumcontaminant levels [MCLS]). The contamination covers an area of approximately2,220 acres. To address the Site’s enviromnental conditions, a Corrective ActionDecision (CAD) was approved by the Kansas Department of Health andEnvironment (KDHE) contained several innovative items, including: (1)alternate cleanup levels (ACLS) above MCLS; (2) containment of thecontamination migration instead of aquifer restoration; and (3) use ofbioremediation to treat the groundwater. Overall the approaches were viewed aspotentially more cost effective than conventional remediation methods. Althoughall anticipated approaches were not implemented, the overall project was veryeffective in achieving goals and cost significantly less than typical groundwaterremediation projects of similar size. The major cost savings resulted from(1) useof ACLS (VS MCLS), which reduced the amount of groundwater requiringcleanup by 40 percent and (2) efficiencies achieved by combining severalcontaminated plumes from many sources into one treatment system. In addition,the treatment system will include many enhancements resulting in recreationaland educational benefits to the citizens of Wichita.

© 2002 WIT Press, Ashurst Lodge, Southampton, SO40 7AA, UK. All rights reserved.Web: www.witpress.com Email [email protected] from: Brownfield Sites, CA Brebbia, D Almorza & H Klapperich (Editors).ISBN 1-85312-918-6

18 Browtzfield Sites: Assessment, Rehabilitation and De~’elopntent

1 Introduction

In 1990, the City of Wichita, Kansas faced a dilemma plaguing cities across theUSA. The Central Business District was declining, aggravated by a weakeningregional oil and gas industry and a slump in the real estate market. Throughpublic initiative and private investment, the City of Wichita (City) sought torevitalize its downtown. However, plans for revitalization abruptly ceased laterin the year as a result of a report from KDHE. The report indicated that thegroundwater under downtown Wichita was contaminated with chlorinatedsolvents. The groundwater plume was more than four miles long and a mile-and-a-half wide, and extended beneath some 8,000 parcels of land, including morethan 550 businesses and thousands of residential properties. The area was namedthe Gilbert-Mosley Site after the intersection of two streets near the center of thearea. The knowledge of this groundwater contamination created concern fromenvironmental, public health and safety, and economic perspectives. Faced withtheir own questions of liability, banks immediately stopped lending to businessand home buyers in the area. Without action, property values within the areawere predicted to plummet by 40 percent. Unless a solution was developedquickly, the federal government would invoke Super fund, aggravating whatalready promised to be a long and costly problem.

The City decided to take the initiative and develop a plan to cleanup the Site,A unique partnership between the public and private sectors was established,involving intergovemmental partnerships with local, state, and federalgovernment support, along with participation from the private sector — banks,responsible parties (industry), and the real estate community. The plan’sfimdamental premise would be the City’s acceptance of responsibility for thecleanup of the Gilbert-Mosley Site in exchange for funding commitments frompublic and private sector partners. With City government in a leadership role, thefollowing actions were taken:

■ The State of Kansas and the City of Wichita established an agreement withthe State’s environmental agency (KDHE) who were acting on behalf of theU.S. Environmental Protection Agency (EPA).

D A primary party, responsible in part for the contamination, signed anagreement with the City to pay for its share of the contamination.

■ The City developed a program agreed to by a majority of the local lendinginstitutions to reestablish lending in this area by using a certificate ofrelease from liability issued by the City,

“ Authored amendments to Kansas State law that were adopted by the KansasLegislature to allow for the use of Tax Increment Financing (TIF) forenvironmental conditions.

■ Created a citizen involvement process for community input and awarenessof the project.

■ Secured a qualified consultant for the job.■ Adopted City Ordinances (institutional controls) to protect citizens from

contaminated groundwater and related environmental conditions.


Browtzfield Sites: Assessment, Rehabilitation and De~’elopntent ~9

As a result of the above actions, life in the Gilbert-Mosley area returned tonormal. Over 4,000 requests for “Certificates of Release” have been received, notonly from property owners within the Gilbert-Mosley Site, but from many on thefringes of the Site, suggesting that the “Certificate” is a good method forremoving potential liability. Overall, the following have been accomplished:

■ Wichita’s citizens have been protected from groundwater contamination.■ The City’s tax base has been preserved.■ The property values in the Gilbert-Mosley area have been preserved and

restored.■ The environment has been protected for fikure generations.~ To the extent that they can be identified, those responsible for the pollution

are paying to clean it up. The remaining costs are being covered by the TIF.In addition to the above positive socioeconomic benefits, many technical

innovations have been implemented. The remainder of this paper describes thetechnical aspects of the project, including innovative approaches to remediation.

2 Site Hydrology

Figure 1 shows the location of the Gilbert-Mosley Site, the Site boundaries, andthe various contamination plumes (A-F). The current Site is approximately 3,850acres in size, covers an area approximately 4.4 miles long from north to south,and varies in width from 1.1 to 2.1 miles from west to east,

The Site is situated within the Arkansas River floodplain. The topography ofthe Site has low relief. The Arkansas River is the most prominent surface waterfeature and flows towards the south near the western border of the Gilbert-Mosley Site and then turns east, south of the Site. Chisholm Creek, which runsbetween I-135, is present at the eastern boundary of the Site.

The geology of the study area primarily consists of Arkansas River Valleyalluvium and associated terrace deposits overlying the Wellington Formationbedrock. The Wellington Formation is primarily a gray and blue shale ofPermian Age, The alluvial sediments consist of interbedded gravels, sands, silts,and clays. The alluvial sediments have a thickness of between 24 and 54 feet andaverages 30 feet on the Site.

Groundwater depths in the alluvial range from 16 to 20 feet across the Siteand average 18 feet below ground surface. Groundwater levels in the alluvialaquifer fluctuate seasonally and may vary as much as 3 feet, depending on theproximity to the Arkansas River, their flow levels, and the amount ofprecipitation received. General groundwater flow is to the south, with a gradientbetween 0.0007 and 0.0014 feetlfoot across the Site. The hydraulic conductivityranges between 380 and 707 feet per day. An average groundwater velocity forthe Site as determined from the calibrated flow model ranges from 1.2 to 1.7 feetper day.


20 Browttfield Sites: Assessment, Rehabilitation and De~’elopntent

3 Problem Definition and Remediation Approach

The present boundaries of the Gilbert-Mosley Site and plume extents weredeveloped as a result of a series of site investigations that have been conductedprivately and by KDHE since 1986. In January 1991, the City selected CDM toconduct the Remedial Investigation and Feasibility Study (RVFS) investigation.The Final RI was approved in January 1994 and the Final FS was approved inApril 1994. After a public meeting, the Final CAD (similar to EPA Record ofDecision) was signed on September 30, 1994.

The groundwater contamination above MCLS covers an area of approximately2,220 acres (see Figure 1). Over 20 individual sources have been identified.Typical regulatory mandated solutions or Record of Decisions (RODS) forgroundwater contamination contain the following components:

Component Specified ActionCleanup Level MCLSGoal of Remediation Restoration of aquifer to drinking water qualityTreatment Method Pump-and-treat

Given the magnitude of the contamination, the large number of sources, andthe questionable ability to restore aquifers to MCLS, the City and CDM proposeda new approach. The rationale for the new approach was provided to KDHE inMay 1993 in a document titled Gilbert-Mosley Site Preferred Alternative. Thedocument addressed each of the typical components of a ROD. The rationaleused in 1993 is summarized in the following sections.

Cleanup Levels and the Goal of Remediation: In the early and mid- 1990s, thefirst of a series of documents became available that evaluated the effectiveness ofgroundwater remediation systems currently in use at a variety of sites ([1], [2],[3]). Conclusions from these reports include:

# In the majority of the cases, the pumping systems were able to achievecontaim-nent of the dissolved phase contaminant plume and the extractionsystems were effective in reducing the mass of contamination from theaquifer.

■ When extraction systems were started up, contaminant concentrationsdropped rapidly but then leveled off (tailing effect). The plateauconcentrations were above remediation goals (e.g., MCLS).

■ Cleanup times and cost were severely underestimated.■ The chemical nature of contaminants and/or the geological conditions of

the Site can prevent pump-and-treat systems from restoring aquifers tohealth-based standards in a relatively short time.

The Comprehensive Environmental Response, Compensation, and Liability Act(CERCLA) requires the attainment of MCLS “where such goals are relevant andappropriate under the circumstances of the release or threatened release. ” NeitherCERCLA or the National Contingency Plan (NCP) require aquifer restorationper se; however, EPA has construed the MCL language to generally obligaterestoration of any aquifer that is a potential drinking water source. The NCP does


Brow field Sites: Assessment, Rehabilitation and De~>elopntent 2 ~

allow for a waiver if the solution is “technically impracticable. ” Since 1993,guidance has been issued concerning the technical impracticability (TI) ofgroundwater restoration [4]. The document provides specific guidanceconcerning the evaluations to be performed to document TI. At Gilbert-Mosley,large areas exist with low concentrations of contaminants. These levels are aboveMCLS but below the concentrations typically achieved during pump-and-treatremediation. Given the historical record of sites not achieving MCLS and the lowconcentrations observed, restoration of the Gilbert-Mosley Site to MCLS may betechnically infeasible.

Overall, the emphasis of any groundwater remediation should be oncontainment (vs restoration), institutional controls, realistic goals, naturalattenuation (if applicable), and frequent re-evaluation of remediation goals. Atthe Gilbert-Mosley Site, a unique combination of approaches to remediationgoals was proposed in 1993. First is the recognition that aquifer restoration toMCLS is not achievable in a reasonable time frame. To design a system for thesole purpose of showing an aquifer may not be restored to MCLS (i.e., to provetechnical impractability) is not a cost-effective approach. The alternativeapproach, to contain the contamination at higher levels and implement higherremediation goals with frequent evaluation, is cost-effective. In fact, the goalproposed (10-4 additional cancer incidents) falls within EPA’s range of acceptablerisk levels. To further minimize any risk to human health, strict institutionalcontrols and public education will be implemented to prevent future groundwaterusage in all areas with contaminant concentrations above MCLS. Remediation toMCLS is also protective of human health, but it is not achievable and it is notcost-effective.

Method of Treatment: The previous reports clearly document theineffectiveness of conventional pump-and-treat technology to cleanupcontaminated groundwater to MCLS. Besides a basic change in the goal ofremediation and the level of cleanup (containment vs restoration, and 10-4 goalsvs MCLS), better treatment technologies are also needed. These technologiesmay include: Soil vapor extraction, air sparging, addition of surfactants or co-solvents (i.e., chemical enhancements), in situ chemical oxidation, monitorednatural attenuation (MNA), reactive barrier walls (e.g., reductive iron), and insitu bioremediation,

4 KDHE and EPA decision

After reviewing the RI data and the technical evaluations in the 1993 PreferredAlternatives (summarized above) and receiving public comments, KDHE (withEPA’s approval) issued a CAD, which is equivalent to an EPA ROD. The CADcontained the following components:

Institutional Controls: Establish institutional controls within the definedboundaries of the Gilbert-Mosley Site. The City of Wichita staff must propose anordinance to the City Council to prohibit the connection of newly-constructedprivate water wells for private or public drinking water purposes. In addition, apublic educational program should be initiated to discourage the use of



groundwater contaminated above the MCLS within the Site. These items havebeen implemented by the City.

Hydraulic Containment: Establish hydraulic containment to prevent fiu-thermigration of contaminated groundwater. Groundwater contaminated aboveKDHE’s ACLS would be targeted for containment. Any recovered groundwaterwould be treated to MCLS for the contaminants of concern. Hydrauliccontainment could be terminated once the ACLS have been achieved andsustained over a one-year period.

Monitoring: Establish compliance monitoring wells at the zero line (i.e., thearea where groundwater contamination is below MCLS) to monitor for thechemicals of concern on a quarterly basis or other frequency as determined byKDHE. If any one of the compliance monitoring wells exceed the federal MCLS,additional remediation would be required. Long-term monitoring would berequired at the compliance and selected monitoring wells for a minimum period of10 years of annual monitoring following termination of hydraulic containment.

Source Control: Individual source control activities must be established at allidentified source areas to eliminate and/or reduce the toxicity, mobility, andvolume of wastelcontaminants at the Site. Source controls will be determined onan individual basis following an appropriate source investigation. Source controlhas been implemented by Coleman (in 1993) and the City (at one site in 1998).

Bioremediation Demonstration: A microcosm study and a field demonstrationwould be performed at the Site to demonstrate the efficiency and economics ofmicrobiological enhancement. The pilot demonstration was completed in 1995.

The CAD describes KDHE’s selection of ACLS at the Site, The levels proposedin the Preferred Alternative (10-4) were modified based upon consideration ofappropriate factors including: exposure factors, uncertainty factors, and concernsregarding cumulative effects of multiple contaminants. The ACLS includechemical-specific 10-5 excess carcinogenic risk concentrations, or federal MCLS,whichever are greater, to address the uncertainties associated with cumulative riskfactors. KDHE’s ACLS, the 10-5 chemical-specific risk levels, and the MCLS areprovided in Table 1.

Table 1: Comparison of MCLs and KDHE’s ACLS (/g/L)

105 Chemical-SpecificContaminant MCLS Risk Levels KDHE’s ACLSTrichloroethene 5.00 21.00 21.00

Tetrachloroethene 5.00 14.00 14.00

1,2-Dichloroethene* 70.00 36.50 70.00Vinyl Chloride 2.00 0.25 2.00

* Not a carcinogen (based on a Hazard Index of 1,0).


Browtzfield Sites: Assessment, Rehabilitation and De~’elopntent 23

5 Application of the CAD

The CAD addresses the three components of concern evaluated in the Prefen-edAlternative document. The application of the CAD results in the followingmodifications to a typical ROD.

Cleanup Level: ACLS were selected versus MCLS for the cleanup criteria.Even though KDHE selected a 10-5 level (VSthe 10-4 recommended), the area ofcontamination needing to be addressed was reduced fi-om 2,220 acres to1,350 acres (see Figure 1). The volume of contaminated water requiringtreatment was reduced from 3 billion gallons to 1.8 billion gallons. This is almosta 40 percent reduction.

Goal or Results of Remediation: Containment was selected versus aquiferrestoration as the ultimate goal of the remediation. As a result, remediationsystems can be installed at the leading edges of the plumes versus within theplumes. The systems will also be installed near the ACL limits instead of theMCL limits,

Cleanup Method: Innovative treatment methods vs conventional pump-and-treat methods were selected by the City as the potential treatment methods. hsitu bioremediation or in situ reductive iron walls were initially selected forgroundwater contaminated with TCE, DCE, and VC. The innovative methodsallow for flexibility in the fiture if newer and better technologies becomeavailable.

6 Progress Since the CAD

Since signing of the CAD in 1994, CDM, the City, and KDHE have worked to:“ Provide better delineation of the ACL extents of the groundwater plumes“ Conduct pilot scale studies to evaluate in situ bioremediation“ Monitor the downgradient extent of the groundwater plumesH Better identify and characterize the source areas within the Site“ Collect data necessary for remedial design and groundwater modeling

efforts■ Conduct groundwater modeling for the remedial design■ Perform preliminary designs for downgradient groundwater remediation

systemsAfter collection of pre-design data in 1995 (groundwater samples to define the

ACL extent and pilot plant evaluation of in situ bioremediation), a draftPreliminary Design Report was completed in March 1996. The report evaluatedtwo remedial alternatives to establish hydraulic containment. These twoalternatives were a pump-and-treat option and an innovative alternative option,which consisted of reactive iron walls and in situ bioremediation. The innovativeoptions were evaluated in order to provide alternatives with less operation andmaintenance and potential overall cost reductions. After input from a CitizensTechnical Advisory Committee and KDHE, the City decided to implement fhll-scale demonstrations of the reactive iron wall and in situ bioremediationtechnologies at Plumes D and C, respectively (Figure 1).



An investigation program to acquire the data needed for the design of theremediation systems was conducted in July through September 1996 and wasreported to KDHE in meetings in October 1996. Based on results of the 1996investigation programs, KDHE concluded that hydraulic containment of PlumeD was already in place via Chisholm Creek (Figure 1). Since the requirement ofthe CAD that a remediation system “establish hydraulic containment to preventfurther migration of contaminated groundwater... ” was met, no remediation ofthe downgradient end of Plume D was considered necessary by KDHE. As aresult, the implementation of the full-scale demonstration of the reactive ironwall technology at Plume D and in situ bioremediation on Plume C was notcompleted.

In order to proceed with remediation on the other plumes, the City and CDMsubmitted Plume Remediation Investigation Work Plans for each of the otherplumes (A, B, E, and F) to KDHE in 1996 and 1997. Investigations associatedwith these work plans were conducted from October 1997 to March 1998. Basedon the new data collected, the City issued a RIIFS addendum in February 1999for Downgradient Plume Remediation. The FS addendum evaluated fourtechnologies in detail: monitored natural attenuation, pump-and-treat, reactiveiron walls, and in situ bioremediation. The four technologies were modified bycombining them into the following alternatives:

‘ Alternative 1 Monitored Natural Attenuation (MNA)‘ Alternative 2a Pump-and-Treat Downgradient‘ Alternative 2b Enhanced Pump-and-Treat~ Alternative 3a Iron Walls and Downgradient Pump-and-Treat■ Alternative 3b Iron Walls and Monitored Natural Attenuation‘ Alternative 4 In situ Bioremediation

A summary of the evaluation and estimated costs for a combined treatmentsystem for Plumes A, B, and E are provided in Table 2. Based on input from amajor responsible party, a Citizens Technical Advisory Committee, and KDHE,Alternative 2a, Enhanced Pump-and-Treat, was selected. The major reasons forthis selection follows:

“ MNA was not effective in meeting the requirements of the CAD and hadextremely long cleanup times. Although PCE and TCE do degradeanaerobically in the site groundwater, the degradation rates are very slowand the degradation does not proceed beyond cis- 1,2-DCE. Thesephenomena exist due to the limited electron donors (carbon) and excesselectron acceptors (sulfate).

‘ h-on walls and in situ bioremediation are new technologies that lack long-term performance data. The technologies are also the most expensive.

■ Pump-and-treat at only the downgradient end of the plume allows lateralexpansion (“smearing”) of the ACL extent and takes a long time,

■ Enhanced pump-and-treat includes additional pumping wells in the plumeto prevent lateral smearing and decrease cleanup times.

The enhanced pump-and-treat alternative was approved by KDHE in October1999. After submittal of preliminary, intermediate, and final design reports,


Browtzfield Sites: Assessment, Rehabilitation and De~’elopntent 25

KDHE approved the final design in October 2000. The Remedial ActionWork Plan was approved in March 2001 and construction commenced inApril 2001. The treatment system will start treating water in June 2002. Asummary of the treatment system components follow:

“ Thirteen extraction wells“ 5.6 miles of high-density underground pipe“ One treatment building with a hydraulic venturi and stripper system■ Design flow rate of 860 gallons per minute (gPm) (maximum of 1,155

gpm)The locations of the treatment building, extraction wells, and underground

piping are shown on Figure 1. The treated effluent water will be dischargedthrough a series of ponds and meandering creeks to enhance the park setting. Thetreatment building will be architecturally enhanced to serve as a display andeducation center, Features will include an educational wing and aquarium. Thecosts for the Plume ABE basic treatment system (without enhancements) follow:

‘ Capital Costs: $5,300,000‘ Average Annual O&M $213,000■ Net Present Value $13,800,000Net present value is for the projected clean-up time of 60 years plus 10 years

of post remediation monitoring.

7 Conclusions

The unique approach by the City of Wichita to this “Brownfields” type projecthave resulted in many benefits, including restoration of property values andredevelopment of portions of the Gilbert-Mosley Site. Several innovativetechnical approaches to remediate the groundwater at the Gilbert-Mosley Sitewere also originally anticipated. A summary of approaches actually implementedfollow:

■ The use of ACLS (VS MCLS) has reduced the amount of groundwaterrequiring cleanup by 40 percent. Although about 10 percent less thanoriginally anticipated, the cost savings have been significant (millions ofdollars).

~ Containment at the downgradient end of the plumes only was shown to beineffective in completely controlling contaminant migration. Additionalextraction wells within the plumes were necessary and helped reducecleanup times significantly.

■ Use of innovative remediation techniques (in situ bioremediation and ironwalls) were determined to be more expensive than pump-and-treatalternatives, In addition, the responsible parties favored more conventionaltechnology versus innovative technologies with no long-term performancehistory.

Overall, the approaches and treatment methods implemented have been themost cost-effective available. In addition, the costs have been significantly lessthan typical groundwater remediation projects of similar size, The cost savingshave resulted from use of ACLS and combination of several plumes from many



sources into one treatment system. In addition, the enhancements to the treatmentsystem will result in increased benefits to the citizens of the City includingrecreational and education facilities. The project has been a true “Brownfields”success story that serves as a model for future sites.


Browtzfield Sites: Assessment, Rehabilitation and De~,elopntent 27

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References

[1] C.B. Doty and C.C. Travis. 1991. The Effectiveness of GroundwaterPumping as a Restoration Technology, Oak Ridge National Laboratory.ORNL/TN- 11866. May.

[2] EPA. 1992. Evaluation of Groundwater Extraction Remedies: Phase II,Publication 9355.4-05 (Volume 1, Summary Report) and 9355.4-05A(Volume 2, Case Studies). February.

[3] National Research Council. 1994. Alternatives for Ground Water Cleanup.National Academy Press. Washington, D.C.

[4] OSWER. 1993. Guidance for Evaluating Technical Impracticability ofGround-Water Restoration. Directive 9234.2-25.


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